Gear testing work holder



y 1946, 1.. D. MARTIN 2,4@3,8

GEAR TESTING WQRK HOLDER FiledJuly 15, 1944 LOUIS D.MARTIN INVENTOR ATTORNE YS Patented July 2, 1946 GEAR TESTING WORK HOLDER Louis D.Martin, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester,N. Y., a corporation of New Jersey Application July 13, 1944, Serial No.544,747

4 Claims.

This application relates to a work holder design for holding spur gearsin a position to be tested in a gear testing machine. One of the objectsof my invention is to provide a work holder by which spur gears may beaccurately held upon a support on which they may be rotated. Anotherobject of my invention is to provide a work holder of the classdescribed which can be accurately located on a gear testing machine andwhich will accurately support a gear in the proper relationship thereto.Another object of my invention is to provide a work holder with a meansfor loading and unloading gears to be tested rapidly while the holder isstill mounted on the gear testing machine. Other objects will appearfrom the fol" lowing specification, the novel features beingparticularlypointed out in the claims at the end thereof.

I have shown two difierent types of gear testing machines in mycopending applications: Serial No. 478,044, filed March 4, 1943, nowPatent 2,369,417, granted February 13, 1945; Serial No. 544,746, forSpur gear testing machines, filed July 13, 1944; and in my Patent No.2,350,788, I have illustrated a preferred form of master worm sectionwhich may be used for testing gear teeth to determine both theaccumulated error in the gear teeth as well as to determine the accuracyof any tooth and the pitch diameter.

The present work holder is especiallydesigned for a gear testing machineof the type shown in mysecond-mentioned application referred to above.Since my present invention is particularly directed to work holders forproperly positioning small gears having fine teeth, I have provided aholder which can be fixedly attached to the gear testing machine andwhich is provided with a means for accurately positioning gears relativeto the machine. Such gears may have only a central opening to support ashaft or may have one or two trunnions extending from the gears so thatit is usually necessary to provide a specific work holder for the typeof gear to be tested. Such holders are intended for use in theproduction testing of gears wherein extreme accuracy is required.

Coming now to the drawing wherein like reference characters denote likeparts throughout:

Fig. 1 is a sectional View through a pinion holding work holderconstructed in accordance with and embodying a preferred form of myinvention;

Fig. 2 is an end elevation of the holder shown in Fig. 1 showing itmounted on a hinged arm which forms a part of a gear testing machine asshown in my second-mentioned copending application;

Fig. 3 is a view similar to Fig. 1, but with the parts drawn out torelease a gear held by the work holder;

Fig. 4 is a fragmentary perspective view showing a second embodiment ofmy invention;

Fig. 5 is a view similar toFigS. 1 and 3, this figure being theembodiment of my invention shown in Fig. 4; and

Fig. 6 is a section taken on line 66 of Fig. 5.

My improved work holder consists broadly in a device carryirv anaccurately-formed pad having a definite relationship to the pitchdiameter of the gearto be tested. I prefer to form this pad at exactlythe pitch diameter of a theoretically'perfeet gear to which the gearto'be tested is made to. conform as closely as possible. The work holderis provided with a means for accurately locating it upon the geartesting machine arm and'wlth a means which will accurately androtatively support a gear to be tested in the correct relationship withthe accurately-formed pitch diameter pad.

More specifically, the work holder shown in the first three figures mayconsist of a support l which consists of a block of metal of any desiredshape On which an accurately-formed pad 2, here shown as being equal tothe pitch diameter of a theoretically perfect gear of the size to whicha work piece gear W is made to conform as nearly as possible. Thesupport i has a cylindrical extension 3 adapted to pass through anaperture 1 in an arm 5 of a gear testing machine, the end 6 of thetubular extension 4 being threaded so that it may be fastened in placeby means of a nut l which is preferably knurled as indicated at 8 inFig. 4 for convenience.

The supporting block i is provided with a shoulder 0 which is adapted toengage a complemental shoulder to as shown in Fig. 4 of the arm 5 so asto locate the block accurately'in position.

The work gear W may be held in place by means of a trunnion 52 having ashank I3 supported by the block i and may be moved to and from thetrunnion [2 when the pad i4 is moved outwardly into the Fig. 3 positionby means of a handle It. The handle 55 is attached to a rod 96 threadedat l! to receive'a nut 28. This nut slides freely in an aperture l9 inthe tubular extension 3. A spring 2!) may be compressed between the nutand the shoulder 2! so that the handle 55 is drawn out against thepressure of spring 2%. By turning the 'block i4 through a small angleafter it has been drawn out, it can be made to rest on t e shoulders 22While the work piece W is being loaded or removed from the trunnion [2.Thus it is an extremely simple matter to load and unload the work gear Wto be tested and this operation can be performed accurately with verylittle effort on the part of an operator.

In the second form of my embodiment illustrated in Figs, 4+6, inclusive,a work gear W is provided with an aperture 30 as shown in Fig. 5, thisaperture being engaged by a tapered section 3| on a removable pin 32carried by the knob 33. This pin is insertable through a bore 34 in theblock 35 to hold the Work gear W in the position shown for testing. Inthis instance the block 35 is provided with a cylindrical pad 35 bearinga definite relation to the pitch diameter which the gear to be testedshould have. I prefer to have this pad on the pitch diameter but it may,nevertheless, vary therefrom by a predetermined extent because intesting gears the pad 36 will be brought into contact with a pad 31 of agear testing tool, the teeth of which 38 are in the form of a wormsection as described in my above-mentioned patent. Thus, the pitchdiameter pad may be contacted with the pad 3las indicated in Fig. 4 todetermine the initial position of the arm 5, this arm having a pad 39engaging a feeler arm 40 of a micrometer. After setting the micrometerto zero, as explained in my second-mentioned application, the teeth ofthe work gear W are meshed with the teeth 38 and any deviation from theproper shape will be registered on the micrometer gauge.

. Returning to the work holder of Figs. 4-6 it will be noted that thesupporting block 35 carries a shaft Mthreaded at 43 to receive a nut 44which holds the shaft in place on the gear testing machine arm 5, theshaft 42 passing through a suitable bore 45 in the arm.

A's with the first-described embodiment of my work holder, it isprovided that a shoulder 46 having a fiat upper surface adapted tocontact with and be located by the complemental shoulder In on the geartesting machine arm 5.

The block 35 is slotted at 41 to receive the work gear W to be tested sothat in this instance the operation of loading and unloading the testgears merely require the removal and insertion of the plug 32 by meansof the handle 33.

The operation of both the embodiments of my work holder is extremelysimilar in that, when a gear to be tested requires a holder, theparticular fixture fOr' positioning the work gear must be designed tothe shape of the gear. However, the holders both have a main block forsupporting the work gear to be tested, a means for rapidly attaching anddetaching gears from the block, an accurately formed pad representingthe pitch diameter which the gear to be tested should have, and a meansfor attaching the work holder in a fixed position accurately upon thearm of a gear testing machine. In both forms of my invention the gear tobe tested may be inserted and removed while the work holder is fixedlyattached to the gear testing machine.

Assuming the gear W is to be tested, the work holder shown in the firstthree figures is attached to the arm 5 by passing the shaft 3 throughthe aperture 4 and turning the nut Z on the thread until the locatingshoulders 9 and I mate and definitely hold the work holder in thecorrect position.

It is then only necessary to insert a gear W on the trunnion l2 whilethe handle I i held outwardly against the pressure of spring 20 and toit engages the gear W as indicated in Fig. l. The

gear may then be tested and removed by reversing the above-describedmovement in so far as withdrawing the handle [5 to the Fig. 3 positionis concerned. Usually, with a single setup a large number of gears willbe tested so that these successive operations can take place quiterapidly, since in testing each gear the operator will merely lower thearm 5 until the pad 2 rests on the pad 31 of the master worm section soas to position the feeler arm 40. With the gauge operated by the feelerarm 40 set to zero the teeth of the work piece are meshed with the teethof the worm section 38 and by noting the deflection of the gauge, whichI prefer to graduate into units of ten thousandths of an inch, theinaccuracy of the teeth may be determined. Thus, a gear held by my workholder can be quickly and accurately tested for pitch diameter and foaccumulated error in the teeth. If it is desired to test individualtooth shape, the testing block may be provided with a single toothspaced from the series of teeth'so that either the single tooth may beused for testing the individual tooth shape or the plurality of teethmay be used for testing all of the teeth by moving the master wormsection a distance sufficient to rotate the gear being tested at leastone revolution.

With the gear holder shown in the last three figures, the operation isexactly the same as that above described except that the work piece W isloaded and removed from a slot 41 and is held in place by the taperedpin 3| operative through the handle 33. It will be obvious that thespecific form of gear supporting device will have to be altered toaccommodate the particular work piece to be tested. If the gears shouldhave trunnions attached, only bearing members would be provided on thefixed part of the work block and the movable member attached to the workblock. Such modifications will readily suggest themselves to thoseskilled in the art.

I claim:

1. A work holder for gear testing machines comprising a slotted support,bearings extending transversely of the slot, a trunnion extendingthrough the bearings and adapted to rotatably carry a gear to be testedand mounted in the slot, a pad on the support having a definiterelationship to the pitch diameter of the gear to be tested and meansfor attaching the support to a gear testing machine.

2. A work holder for gear testing machines comprising a support, meansfor rotatably attaching a gear to be tested to said support, a padformed on the support havin a predetermined relationship to the pitchdiameter of the gear to be supported thereby, said means for rotatablyattaching a gear to the support including said support and a partmovable relative thereto, said part movable relative thereto holdin saidgear to be tested when moved into an operative position, and a springtending to move the part movable relative thereto into its operativegear holding position.

3. A work holder for gear testing machines comprising a support, meansfor rotatably attaching a gear to be tested to said support, a padformed on the support having a predetermined relationship to the pitchdiameter of the gear to be supported thereby, said means for rotatablyattaching a gear to the support including said support and part movablerelative thereto, said part movable relative thereto holding said gearto be tested when moved into an operative position, and a spring tendingto move the part movable relative thereto into its operative gearholding position, a rod supporting said part movable relative theretofor slidably mounting said lastmentioned part on said support.

4. A Work holder for gear testing machines and comprising a support,means for mounting a

